College of Engineering News • Iowa State University

Tan’s lead-free piezoelectrics discovery published in Physical Review Letters

Xiaoli Tan
Xiaoli Tan

Associate Professor of Materials Science and Engineering Xiaoli Tan’s research to examine the morphotropic phase boundary, or a state of compounds with a coexisting crystalline phase, in lead-free piezoelectrics was recently published in Physical Review Letters (PRL), the world’s foremost physics journal.

Tan and graduate students Hanzheng Guo and Cheng Ma, along with MSE Assistant Professor Scott Beckman, studied a lead-free ceramic system to explore electric field-induced microstructure changes and their impact on the piezoelectric property. He says their research can contribute to improving energy efficiency while also helping the environment.

“Piezoelectric materials enable the conversion between electrical and mechanical energies, and they have been used in many important applications, such as devices for ultrasound medical imaging and for energy harvesting from vibrations,” Tan explained. “During the past six decades, lead-containing ceramics (greater than 60% weight of lead) have dominated piezoelectric technologies even though they pose a serious threat to the environment and human health.”

Intensive worldwide efforts have yet to succeed in identifying replacement lead-free materials with comparable piezoelectric performances, but Tan hopes his recent research can change that.

The group discovered that the morphotropic phase boundary and the associated high piezoelectric performance could be created from compositions that are excluded by general guidelines based on early experiments. Their findings provide fundamentally new principles for achieving strong piezoelectricity, which breaks the ice for realizing environmentally friendly lead-free piezoelectrics with superior energy conversion efficiencies. Moreover, Tan adds, these principles will inspire the development of other functional materials.

His research was presented in the paper “Creation and Destruction of Morphotropic Phase Boundaries through Electrical Poling: A Case Study of Lead-Free (Bi1/2Na1/2)TiO3–BaTiO3 Piezoelectrics,” which was included in the September 7, 2012, issue of PRL.

The U.S. National Science Foundation sponsored the research presented in this paper.

Tan’s work was also featured in Ceramic Tech Today on September 11.